First off you might be asking yourself, ‘What is SD?’ SD stands for Secure Digital. SDHC? Secure Digital High Capacity. And SDXC? Secure Digital eXtended Capacity.
SDXC vs. SDHC vs. SD Card
SDXC cards are essentially a higher capacity version of the SDHC card (which itself is a higher capacity version of the original SD card). SDXC cards start at capacities of 64GB and can grow to a maximum theoretical capacity of 2TB. Just as with previous versions, there is a smaller “micro” version designed for small devices such as cell phones, but more on that next week.SDXC Card Speed
In addition to offering higher capacities, SDXC cards are also capable of faster data transfer speeds, with a maximum speed of 300MBps. In contrast, SDHC cards can achieve up to 10MBps. To help you find the right speed, SD/SDHC/SDXC cards are broken down into four classes: Class 2, Class 4, Class 6 and Class 10.
Class 2 cards offer a minimum sustained data rate of 2 megabytes per second (MBps), Class 4 of 4MBps, Class 6 of 6MBps and Class 10 of 10MBps. Depending on which manufacturer is selling the card, the speed class will either be prominently displayed or buried in the specs. Either way, you should keep an eye out for it.
For standard definition cameras, an SD/SDHC card with a Class 2 speed is all you would need. It’s fast enough to handle the highest quality standard definition video you can record. For high definition cameras, cards with a Class 4 or 6 speed rating are fast enough to handle the data transfer rates of even the highest end high definition cameras.
In many cases, SDXC cards will be offered in faster speeds than you need for a digital camera. These faster speeds offered by SDXC cards are useful for digital cameras – it enables them to have ultra-fast burst modes, however, they’re not necessary.
SDXC Card Compatibility
One question around any new card format is whether it will work in older devices, or whether newer devices will accept older card formats like SDHC and SD. To answer the first question, an SDXC card may work in an older device that doesn’t specifically support it, but you won’t enjoy the larger capacities or faster speeds. Most cameras and camcorders introduced in 2011 support SDXC. Support is more limited in cameras and camcorders introduced in 2010. If a camera takes an SDXC card it will always work with SDHC and SD cards.